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22 January 2013

Tragedy: Columbia

[Originally posted July 25, 2012, re-posted, now, as the tenth anniversary of the tragedy approaches.]

On February 1, 2003, the Space Shuttle Columbia, Mission STS-107, broke apart over Texas killing the crew of seven astronauts after sixteen days in space.  The disaster was precipitated by damage to the left wing sustained on launch from a piece of foam insulation falling from the external fuel tank and striking the leading edge of that wing.

A cracked or dislodged ceramic tile or cracked leading edge of reinforced carbon-carbon of the left wing allowed the hot gasses experienced by spacecraft during reentry to either shear or melt-through portions of the wing structure, ultimately causing a total breakup of the spacecraft.

The crew of seven were Rick Husband, Commander; William McCool, Pilot; Michael P. Anderson, Payload Commander; David M. Brown, Mission Specialist 1; Kalpana Chawla, Mission Specialist 2; Laurel Blair Salton Clark, Mission Specialist 4; and Ilan Ramon, Payload Specialist 1.

The events with commentary. 

    Times are listed in Houston, Texas (Mission Control) time.
    FDL = Flight Director's Loop, with time indexed
    OBV = On-Board Video, with time indexed
    (see "Resources" section, below)

07:41:29 (FDL 1:10/ OBV 2:29) “Yep.

On the Flight Director’s Loop (FDL) is heard, but not transcribed, a short voiced, “Yep” or “Yip.”  Due to the very few transmissions received from the shuttle in its last hour, some had wondered if this may have been an expression of surprise by one of the crew.  However,  both William McCool and Kalpana “KC” Chawla use the term, “Yep,” frequently.  

It is not clear if McCool (the only person aboard the shuttle, other than Husband, who would be heard on the FD loop) had uttered the word and inadvertently keyed his mic; but, at this point in the flight, it is clear from the video and from flight data that nothing unusual is taking place.  In fact, Entry Interface (EI) has not yet begun, so the spacecraft is not undergoing any stress or heating.

07:44:09 (FDL 3:50/ OBV 5:09) Entry Interface.  The shuttle first enters the Earth’s atmosphere at about Mach 25 and 400,000 feet in altitude.  Nothing on either recording signifies this technical fact.  It is mentioned, here, because it is the first moment in which the vehicle begins to make contact with the atmosphere.

07:49:00 (FDL 17:39) The portion of the on-board video released by NASA to the public ends here.

Some, mistakenly, believe that the video “breaks-up” at this point coincident with the shuttle breaking up. The shuttle is flying normally and the cabin is unaffected by whatever damage may have begun. The crew was above the Pacific Ocean, about 260,000 feet up, traveling at Mach 24.56.

Whether there is any usable video after this point is not clear.

07:49:47 (FDL 18:28) “Roll ‘em right.
This unidentified voice (probably in Houston) may be making mention of the first right hand roll of the shuttle which was initiated fifteen seconds prior to this comment.   As the craft slows, it commences an “S-turn” maneuver: rolling right, then left, then back right, to bleed off speed.

07:49:49 (FDL 18:30) “?-dis-eleven
“Eleven” being the only full word heard, this voice is unidentified and immediately follows the different voice mentioned above. The phrase is abrupt and perhaps emphatic, but there is no evidence from the telemetry that those on board the shuttle might have any cause for either stress or alarm. The shuttle is not yet five minutes into the entry-interface (EI) and the first indication of trouble with the left wing (the four failed hydraulic transponders) does not begin for another three minutes and ten seconds.

Note that this is less than one minute after the released (but not necessariuly full) version of the on-board video ends, which gives cause for consideration. It is almost nine minutes before any communication with the astronauts is heard again.

A possibility:  When the external pressure reached 2 pounds per square foot (Qbar) the wing control surfaces become activated as they then can become useful for controlling the shuttle as it enters the atmosphere. At 10 psf, the roll jets are deactivated as they are no longer needed. This threshold was reached moments before this transmission.  It is possible that a NASA engineer inadvertently keyed a mic while discussing this phase of the descent with another, perhaps referring to the current telemetry indicating eleven psf.

07:52:59 Four hydraulic transducers wired in common along the leading edge of the left wing, just where the foam insulation struck the wing at launch, begin to fail—all four go “off-scale-low” (OSL) within about 30 seconds.

In hindsight, the sensor wiring was sheared by the plasma encroachment due to a broken or missing ceramic tile which served as the shuttle's heat shield during re-entry.  At the time, Mission Control was assuming that the sensors had simply been knocked loose by the foam impact incident during launch.  The sensors failures occurred as follows:
  • 07:52:59
  • 07:53:10
  • 07:53:11
  • 07:53:32
07:53:28 The shuttle crosses the coast over California. The group responsible for monitoring and diagnosing the shuttle telemetry, MMACS (pronounced, "macks"), is concerned about the new data. Meanwhile, and unknown to Houston, video from television and amateur recordings indicate signs of debris falling from the shuttle:

(See Notes concerning Video and Photo Evidence below this section).
  • 07:53:46 Debris #1
  • 07:53:48 Debris #2
  • 07:53:56 Debris #3
  • 07:54:02 Debris #4
  • 07:54:09 Debris #5
07:54:24: (FDL 22:49) MMACS calls the Flight Director and says, “FYI, I just lost four separate, uh, temperature transducers on the left side of the vehicle-- the hydraulic return temperatures. Two of them on system one, and one each on systems two and three.

As MMACS and the Flight Director discuss the transducer failures.  The commonality is quickly determined to be in the position of the wiring of these sensors, all on the leading edge of the left wing.   Mission Control is also checking for other signs that the shuttle may be in danger. Its flight characteristics are normal, but other data is beginning to show that the flight control surfaces are having to work harder than usual to keep the shuttle on course, and that some sensors are indicating temperatures slightly higher than expected.

While Houston remains unaware of the video evidence of debris trailing behind the shuttle, the situation is quickly degrading as it passes over Nevada, Utah, Arizona, New Mexico and into Texas.  Several amateurs and local television stations in those states videotape the shuttle as it passes overhead:

  • 07:54:33 A bright flash is seen on video taken of the shuttle.
  • 07:54:36 Debris #6 (one of the two brightest debris events, and so probably more significant)
  • 07:55:05 Debris #7
  • 07:55:23 Debris #8
  • 07:55:26 Debris #9
  • 07:55:27 Debris #10
  • 07:55:37 Debris #11
  • 07:55:45 Debris #12

  •  07:55:49 The shuttle now enters sunlight, dawn.  More local video records continued damage:
  • 07:55:56 Debris #13
  • 07:55:58 Debris #14 (the second of two bright, and so probably large, debris events)
  • 07:56:10 Debris #15
  • 07:57:24 Debris #16
  • 07:57:54 Flare 1 (Photographed by personnel at Kirtland Air Force Base, NM)
  • 07:58:00 Flare 2 (From the same armature photo set as above.  This is the final piece of external evidence prior to LOS and until the video of the main break up near Dallas, Texas)
07:58:38 Shuttle tire pressure sensors begin to fail.

07:58:40 MMACS begins to report the tire sensor failures it has received from telemetry.

07:58:44 (FDL 27:10) “and, uh, Houst—” Four seconds prior to this, Husband and/or McCool would have seen a fault indication from the Backup Flight System (BFS) concerning the Tire Pressure. 

Some have transcribed this as "Feelin' the heat." Most transcripts render this otherwise, usually as, “and, uh, Houst—“ and as a broken, or interrupted, transmission. It has been noted that it does not make sense to start a sentence with a conjunction, yet the transcript shows that Husband does this often, “and, uh, Houston” is almost certainly the correct transcription of what was being said. The voice is calm, the conjunction, “and” suggests the intent to pass information or to ask a question.

07:59:02 (FDL 27:39) MMACS calls the Flight Director with the new information about tire pressure, “We just lost, uh, tire… pressure on left outboard and left inboard, both tires.

07:59:09 (FDL 27:46) CAPCOM calls Columbia to state that Houston can see that astronauts have a BFS Fault warning on the shuttle's console. “And Columbia, Houston, we see your tire pressure message and we did not copy your last."  Mission Control is also acknowledging receiving a partial voice transmission.  "Did not copy your last" would be expected to provoke the astronaut to repeat the previous transmission.

07:59:16 (FDL 27:53) “Roger, and uh—“ These are the last words received from the shuttle.  Ten seconds earlier, an on-board indication that the left landing gear was in the deployed, "down and locked," position had been seen by the astronauts.  This is probably an electrical malfunction from damaged sensors as the "up-lock" indicator remained on.  The "down-locked" indication is the most likely message content intended by the astronaut when the transmission was interrupted.

Communication is often intermittent during this stage of re-entry, so it is not clear if the transmission was interrupted by events taking place on board the shuttle or due to the more prosaic reasons.  There is no indication of stress in the voice.  In saying "Roger," the astronaut is stating that he understood the previous message.

THE LIVES OF THE CREW are lost sometime in the next ninety seconds.  Loud alarms sounded within the crew compartment, the interior lighting went dark, the shuttle began to tumble, rapidly, end over end as McCool worked controls until the cabin tore open. 

That McCool was working the controls, a detail released by NASA, might reasonably be interpreted as the result of having recovered more of the on-board video than has been released; however, NASA has hard evidence of this detail.  Specifically, the control panel before McCool's seat was found on the ground in Texas.  The manual switches were mechanically held in their last position (a feature of the switches to prevent accidentally bumping) and the switch settings clearly show that the astronaut was attempting to restart failed Auxiliary Power Units (APU).

While the suits the astronauts wear could protect them from the explosive-decompression, none had the visor down and sealed at break-up.  Furthermore, the pressure suits were unable to provide protection when exposed to the same forces which caused the shuttle to disintegrate.  It is believed that all seven were unconscious within six seconds of the cabin breach and probably dead prior to the cabin break up.

Steve Douglass photo from Amarillo, Texas.
Note the irregular track.

Over the next few seconds, detailed below, Mission Control is trying to find commonality between other data of concern, as other sensors are displaying erratic or unexpected data.

07:59:30 Altitude 200,676 feet, Mach 18.6. Last telemetry before loss of signal (LOS). Communications, expected to be bad, are worse than expected.  Reconstructing the final data, all telemetry from the left wing sensors failed at about this moment.

07:59:37 LOC (Loss of Control).  The hydraulic lines which powered the wing's control surfaces were severed.  Based on recovered data, the shuttle was still on autopilot, one astronaut bumped the control stick and quickly entered the key sequence to reinstate autopilot.  The crew cabin still retained normal pressure, and power and lighting (including instrumentation) were still available.

07:59:46 The Columbia is beginning to twist out of control about forty miles west of Fort Worth.

07:59:46 (revised from 08:00:04) Debris A (first major section of shuttle breaks away-- believed to be the left OMS Pod Cover).

08:00:02 (rev. from 08:00:17) Debris B (probably a portion of the left wing)

08:00:03 (rev. from 08:00:20) Debris C (another portion of left wing)

08:00:04 Last data (partial and corrupted) received from shuttle telemetry.

08:00:05 (rev. from 08:00:18) onset of Main Body Break up.

08:00:40 Crew Cabin break-up.  At main body break up (above) crew cabin began to separate from the rear portion of the shuttle.  The analysis of the data and the recovered debris suggest that the cabin was probably breached at about this time, first with small leaks and then with more catastrophic holes.  None of the crew had their helmet visors down, so the effect, on the astronauts, of depressurization was nearly immediate, and bringing about unconsciousness or death-- no longer breathing.

As mentioned above, the console which had been before Shuttle Pilot McCool's seat was found and the switch positions noted.  The switches are mechanically locked in position.  While none of the astronauts had time to complete the task of lowering their visor to seal their suits (indicating how quickly the depressurization incapacitated them), McCool had reset the switches from the last known position so as to attempt a restart of the two Auxiliary Power Units (APUs) which had failed at the main body break-up.

Review of the data strongly suggests that the astronauts' lives were lost instantaneously, due to the violent forces of the tumbling and break-up of the vehicle-- much like in a high-speed automobile accident in which unconsciousness and death are effectively simultaneous.

While the ground had been aware of the potential damage to the left wing at launch, the crew was not informed of this.  Consequently, while Mission Control was more prepared to fear the worst as the sensors began to show abnormal readings, it was only the last 90 seconds in which the crew could have begun to suspect a catastrophic problem might be developing, and based on McCool's attempts to restart the power unit during that time, the crew seemed to believe that they could recover from the failures up until the moment of unconsciousness.

AT MISSION CONTROL, unable to reach Columbia, radars are set to scan, but fail to lock.  Attempts to raise the crew using UHF are met by silence.

The eye-witness and video reports are beginning to come in to local television stations in the Dallas/Fort Worth area.  Word of a broadcast made by WFAA TV in Dallas on behalf of CNN reaches Mission Control Manager, Phil  Engelhauf (11:51 into video to right).  The video, described to him, clearly shows that the Shuttle is in pieces.  It has broken up.

Engelhauf looks to his right and sees astronaut and Deputy Director of Flight Crew operations, Ellen Ochoa.  He tells her the shuttle has broken up over Dallas.  Her face shows agony.
Engelhauf then stands and tells Flight Director LeRoy Cain the same news. After a brief discussion, the Flight Director turns away, to refocus the Mission Control Center.

08:03:34 The last pieces of the shuttle impacts the ground.  Sonic booms left by debris having dropped from the main body long before the final break up are heard in areas as far west as Fort Worth, Texas, and debris rains down in a path ranging from there to western Louisiana.**

08:12:32  (FDL 41:13)  Cain says, “GC, flight, Lock the doors.” That statement was understood by all those present.  The mission was no longer about saving lives, but about saving data. The expression is as figurative as it is literal.  Mission Control is in lock-down, no persons, data, or communication is to come in or to go out except between Mission Control and recovery forces.



Several resources were used in this study of the events of the final hour of the Columbia and her crew.  The focus was to present a narrative of events with a passing acknowledgment of the existence of several popular, but factually incorrect, assertions found on the Internet.
Source data and links (all times in Central Standard Time):
FD Loop  07:31:19 to 08:29:52
Interspacenews transcript 07:32:34 to 08:30:05
On Board Video  07:39:00 to 07:49:00 (see transcript)

Time stamps are approximate, and adjusted from other estimates to known timing of specific events.

Video and Photo Evidence

Amateurs and various agencies provided images of the Shuttle's Reentry which were analyzed for clues as to the timing and severity of visual anomalies. Each video or still image source is given a serial identification code as EOC2-4-00##.  Important video evidence of reentry debris are as follows:

EOC2-4-0064 07:53:13 - 07:54:17 (Lionel Machado, Fairfield, CA)
EOC2-4-0055 07:53:38 - 07:54:51 (Jay Lawson, Sparks, NV)
EOC2-4-0034 07:54:04 - 07:54:45 (Reno, NV)
EOC2-4-0056 07:53:28 - 07:54:29 (Rick Baldridge, Mt. Hamilton, CA)
EOC2-4-0009B 07:54:17 - 07:55:13 (John Sanford, Springville, CA) *
EOC2-4-0030 07:54:37 - 07:56:06 (Paul Adams, Las Vegas, NV)
EOC2-4-0017 07:54:45 - 07:57:30 (Chris Valentine, North of Flagstaff, AZ, seen above)
EOC2-4-0028 07:55:05 - 07:56:02 (St. George, UT)
EOC2-4-0021 07:55:13 - 07:56:16 (St. George, UT)
EOC2-4-0005 07:55:18 - 07:56:10 (Ivins, UT)
EOC2-4-0050 07:55:31 - 07:55:55 (St. George, UT)
EOC2-4-0018 07:59:41 - 08:00:05 (Bob Butsch, WFAA, Duncanville, TX, seen above)
EOC2-4-0024 07:59:42 - 08:00:17 (McNew, Arlington, TX)

EOC2-4-0025 08:00:21 - 08:01:19 (Camp Swift, TX)
RV2  08:00:26 - 08:01:19 (Apache Helicopter video, Ft. Hood, TX)


Chris Valentine compiled most of the above and produced an excellent video entitled, Columbia Reentry Reconstruction.    Besides portions of videos contained elsewhere in this article, including Mr. Valentine's own, it contains clips of the following videos which cannot be found anywhere else on the web: Mt. Hamilton, CA; Sparks, NV; Las Vegas, NV, Irvins, NV; at least one of the three from St. George, UT; Kirtland AFB, NM; and what may be the Camp Swift, TX, video:

Alternates: The WFAA/TV broadcast, EOC2-4-0018. Short version of McNew, EOC2-4-0024.


* The significant time adjustments stem from an oft reproduced error in an early NASA report.
* Several good sources for the Scott Lieberman image taken from Tyler, Texas:, and  and this interview...
YouTube video


** Editor's note:

At 08:00:02, Columbia passed over my home in Alvarado, Texas, thirty miles south of downtown Fort Worth.  Two to four minutes after passing, the ground rumbled and overlapping sonic booms were heard as many pieces of lower-flying debris passed overhead at multiples of the speed of sound.  Calculations suggest that any debris passing near overhead would have been in free-fall for at least two minutes-- that is, probably debris from (or after) the "07:59:30" event. (last update, 21-Jun-2013)

-- W. Crews Giles, copyright 2012, 2013, all rights reserved.

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